What are Firewalls? Here's a Complete Explanation

what are firewalls heres a complete explanation.

A case study says that on average, hackers hack into an unsuspecting user's computer every 39 seconds. As cybercrime continues to increase. Protecting your sensitive data is something you should do using a firewall is the first line of defense. So in this article, we will discuss what a firewall is in full.

What are Firewalls?

Firewalls are systems in the form of software or hardware designed to prevent unauthorized access to individual computers or computer networks. They are mostly used as the first line of defense to protect your device or network from online threats such as hackers, viruses, Trojans, and worms.

Every time you connect to the Internet, your computer is exposed to all kinds of malicious programs and malicious people who want to infiltrate your computer to steal your personal information, send spam emails to your inbox, or use your computer to launch attacks against other people.

A good firewall system prevents attackers from trying to infiltrate your system and prevents your data and information from flowing to criminals.

How Do Firewalls Work?

Firewalls carefully analyze incoming traffic based on predefined rules and filter traffic coming from unsafe or suspicious sources to prevent attacks. Firewalls protect traffic at computer entry points, called ports, where information is exchanged with external devices. For example, “Source address is allowed to reach destination via port 22.”

Think of the IP address as the house, and the port number as the room in the house. Only trusted people (source address) are allowed to enter the house (destination address). Then it is filtered again so that people in the house are only allowed to access certain rooms (destination ports) and it depends on the owner. Suppose the owner is allowed to any room (any port), while children and guests are allowed to enter a certain set of rooms (certain port).

So a firewall acts as a traffic guard at your computer's entry point or port. Only trusted sources, or IP addresses, are allowed in. IP addresses are important because they identify a computer or source.

Types of Firewalls

Firewall types can be divided into different categories based on their general structure and method of operation. The following are some types of firewalls:

  * Packet-Filtering Firewall

  * Circuit-Level Gateway

  * Stateful Inspection Firewall

  * Application-Level Gateway (Proxy Firewall)

  * Network Address Translation (NAT) Firewall

  * Next-Gen Firewall

  *Firewall software

  * Hardware Firewalls

How do these types of firewalls work? Here are some brief explanations:

Packet-Filtering Firewall

Packet-Filtering firewall is a management program that can block network traffic IP protocol, IP address, and port number. This type of firewall is the most basic form of protection and is meant for smaller networks.

While packet-filtering firewalls can help, they also have limitations. Since all web traffic is allowed, it does not block web-based attacks. So, you need additional protection to differentiate between friendly and malicious web traffic.

Circuit-Level Gateway

Circuit-Level Gateway is a type of firewall that functions by verifying the transmission control protocol (TCP) handshake. This TCP handshake check is designed to ensure that the session from the packet is legitimate.

Although very resource-efficient, this firewall does not check the packets itself. So if a packet contains malware, but has the proper TCP handshake, it will escape.

Stateful Inspection Firewall

A stateful Inspection firewall combines packet inspection technology and TCP handshake verification. It offers better security than packet-filtering or circuit-level.

But unfortunately, this type of firewall demands a greater burden on network performance. Which can slow down legitimate packet transfers.

Application-level Gateway (Proxy Firewall)

A proxy firewall filters incoming traffic between your network and traffic sources at the application level hence, its name is "Application-Level Gateway". Unlike a basic firewall, a proxy acts as an intermediary between two end systems. The client must send a request to the firewall, which is then evaluated against a set of security rules and then allowed or blocked.

Most importantly, proxy firewalls monitor traffic for layer 7 protocols such as HTTP and FTP and use stateful and deep packet inspection to detect malicious traffic. But there is one drawback to these proxy firewalls, which is that they can create significant slowdowns due to the extra steps in the process of sending data packets.

Network Address Translation (NAT) Firewall

Network Address Translation (NAT) Firewalls allow multiple devices with independent network addresses to connect to the internet using a single IP address, thereby hiding each IP address.

As a result, attackers scanning the network for IP addresses are unable to capture specific details, providing greater security against attacks. A NAT firewall is similar to a proxy firewall in that the firewall acts as an intermediary between a group of computers and outside traffic.

Next-Gen Firewall

Next-Gen firewalls are more sophisticated than packet-filtering and stateful firewalls. Why? They have more levels of security, going beyond standard packet filtering to check the whole packet.

Next-Gen firewalls combine traditional firewall technology with additional functionality, such as encrypted traffic inspection, intrusion prevention systems, anti-virus, and more. Primarily, it includes deep packet inspection (DPI).

While a basic firewall only looks at the packet header, deep packet inspection examines the data within the packet itself, allowing users to more effectively identify, categorize, or terminate packets with malicious data.

Firewall Software

Software firewalls include all types of firewalls that are installed on local devices rather than separate hardware (or cloud servers). The great benefit of software firewalls is that they are very useful for creating deep defenses by isolating individual network endpoints from each other.

However, maintaining individual software firewalls on different devices can be difficult and time-consuming. In addition, not every device on the network may be compatible with a single firewall software, which may mean having to use several different firewall software to cover each asset.

Hardware Firewall

Hardware firewalls use physical devices that act in a similar way to traffic routers to intercept data packets and traffic requests before connecting to network servers. Physical appliance-based firewalls such as these excel at perimeter security by ensuring malicious traffic from outside the network is intercepted before enterprise network endpoints are exposed to risk.

However, the main weakness of hardware-based firewalls is that it is easy for insider attacks to get through. And also the actual capabilities of the hardware firewall may vary depending on the manufacturer.

The Risks of Not Using a Firewall

You may already be engaged in safe computer and internet use practices, including the following:

  * You don't click on unknown links or attachments.

  * You only go to trustworthy and known websites.

  * You never provide any personal information unless it is absolutely necessary.

  * You have a strong, unique, and complex password for each online account that you update frequently.

Does that make you safe enough? The answer is probably no. If you use the internet, you should have an active firewall on your computer. Cyber ​​threats are widespread and growing. It is important to use available defenses to help protect your network, and personal information stored on your computer, against cybercrime. Here are the three main risks of not having a firewall:

Open Access

Without a firewall, you accept every connection to your network from anyone. You will have no way of detecting incoming threats. It can make your device vulnerable to malicious users.

Lost Or Interrupted Data

Not having a firewall can expose your device, which could allow someone to gain control over your computer or network. Cybercriminals can delete your data. Or they can use it to commit identity theft or financial fraud.

Network Jam

Without a firewall, attackers can shut down your network. Running it again, and trying to recover saved data, can cost you time and money.

Firewalls are an important part of security technology, especially when different types of firewalls work together to provide protection. Firewalls can help keep your network, computers, and data safe and secure.


So What is a Firewall? A firewall is a type of cybersecurity tool that is used to filter traffic on a network. The way a firewall works is basically, it checks all the data trying to pass it on to determine whether to forward it to its destination. Firewalls are also one of the many solutions available in today's cybersecurity world for controlling external threats.

Hopefully, this article about What are Firewalls? Here's a Complete Explanation, gives you a little insight. Also, read an article about What are Functional Programming Languages that you may need to know. Thank you.

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